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Discussion Starter #1 (Edited)
How much difference will a gear change give you? I have a 72 nova with the stock limited slip and 308 ring and pinion. It has a mild 350 with a th350 trans and is a dog off the line. I was told by the guy I got it from the motor is fresh with a mild cam. In doing a little research I have found it has 76 cc smog heads on it and an even 150 pounds of compression on all cylinders. Im in a debate on which route will give me the takeoff I desire. I have purchased a set of fresh 327 camel backs with 62 cc chambers and a fairly moderate cam, lunati voodoo with 268 duration and good lift but I also purchased a 373 ring and pinion. I have the funds to do either upgrade but not both. Any suggestions as to which will be more beneficial? Here is a little more info on the cam it has a 268/276 advertised duration and 489/504 lift. I also have a 1500 stall converter in the trans. Well it flashes at 1500 anyway. Thanks in advance for any advice or suggestions.
 

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Changing the gears from 3.08 to 3.73 will make you faster off the line but will give you a higher rmp so gas mileage will suffer. I'm changing the other way from 3.70 to 3.50 because at 80 mph on the freeway I'm running 2800 rpm.

Good luck
 

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Discussion Starter #3
Thanks for the heads up. I think I'm around 2000 rpm at freeway speeds currently. Gas mileage isn't an issue really for me this car is more of a toy rather than daily driver. What do you think I could gain with the engine upgrades?
 

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To be perfectly honest I'm not sure the exact mph. My speedo is inop. I think the guage is seized. Just keeping up with traffic in a 65 mph zone I figured is about 70 give or take. The trans does not have overdrive. The stock rearend in the car is 308 and from everything I gather it has not been altered. Its the original 10 bolt I know that much. I guess the true tell would be to pull the cover and count the teeth. Maybe the gears are taller than 308? Knowing that I should get even more pickup off the line with 373 gears right? I am just trying to get the best improvement for the buck I suppose.
 

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2 questions come to my mind. 1st how much money do you have to spend? 2nd is how mechanically inclined are you. The reason I ask is if I read your post correct you have all the parts purchased correct?
 

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Discussion Starter #7
I have all the parts except the gaskets. No head gaskets or others. I have complete confidence in doing the cam and heads swap but none whatsoever in doing the rear end. I found a shop in salt lake to do the gear swap for 200 bucks. I figure I would spend that on gaskets. That just happens to be the bottom of the bucket of cash for now. I thought about diving in to the rear end myself but lack the experience with gear setup. I can do one now and the other project in a month or so. Just looking for opinions on which change would give more improvement is all. Just looking for more torque. The motor pulls hard through 5500 rpm just slugish of the line.
 

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I should get even more pickup off the line with 373 gears right? I am just trying to get the best improvement for the buck I suppose.
Moving from 3.08 to 3.73 will definitely improve your low end performance; but there is always a downside - that being you will be turning more RPM's on the freeway.

QUOTE=MYETTER;1900736] I think I'm around 2000 rpm at freeway speeds currently. /QUOTE]

You may actually have something like 2.73 gears if you are only turning 2000 RPM on the freeway.
 

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I just went from 370 to 411. With 26" tires its spinning over 3000rpm in the slow lane barley keeping up with traffic. I did pick up a 10th on my 1/8th mile time. Ive got an overdrive trans in the works. You'll want it with tose gears.
 

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Just looking for opinions on which change would give more improvement is all. Just looking for more torque. The motor pulls hard through 5500 rpm just slugish of the line.
Do the gears, you will really feel the difference. Keep the cam for installation at a later date when you do the head change. Sell the humps and save for better heads down the road. You will get WAY more power that way. Jack
 

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I think if you have the ability to do your heads then do that first. When you get the extra cash do the gears. Did you buy a new carrier for the gears? I am pretty sure 373 will need a new carrier.
 

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Discussion Starter #14
Just got home from work and took the freeway. I was way off on my previous statement about my rpm's at freeway speeds. It is spinning faster than I posted earlier. Keeping up with traffic im turning closer to the 3000 rpm range. Not positive on the mph, need to fix my speedo or use a gps to get an accurate readout. Thank you everybody for the thoughts I am very grateful! I will post an update later this week with the results and what I decide to do. Either way I will be driving it again come wednesday! Hopefully I can get some pics posted as well. Thanks again!
 

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I finally got some pics up if anyone is interested in looking at the car im talking about!
 

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x 2 on that. I am going from a 2.73 to a 4.10 one day when I buy the Eaton posi.:yes:
x 3 on the gears.... They are torque multiplyers. Best bang per buck for performance for sure. Do a calculation for trap speed verses rpm to figure how low to go. Doing a small ratio change may be dissapointing, you can fine-tune the change with a tire size adjustment.
 

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I too have 3.08s, with a 26.5" tall tire, which ends up being right around 2550rpm at 65mph with a TH350.

I've considered going up to a 3.42, but that would be my limit. This would put me at 2800rpm at 65mph, or if I drop my cruising speed to 60mph than rpms would be right around 2600. I have no plans whatsoever to install an OD trans, so 3.73s are probably not something that I will consider.

Having said that, if you don't like the higher cruising rpms of the 3.73s, you might want to consider a looser stall speed to get some noticeable gains at launch. I've got a 2000 right now, and it comes off the line much harder than a stock stall even with the little 3.08s. I think I will probably bump that up to a ~2400 even with my mild cam. Your 1500 is pretty tight, and I think you'd see some noticeable gains by loosening that up. Not to mention, a looser stall will be a good thing once you install that bigger cam in the future.
 

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x 3 on the gears.... They are torque multiplyers. Best bang per buck for performance for sure. Do a calculation for trap speed verses rpm to figure how low to go. Doing a small ratio change may be dissapointing, you can fine-tune the change with a tire size adjustment.
I tell the same thing to a buddy at work who has a 2001 Mustang. It has overdrive so all he needs to do is put some gear in it and wake it up.

Mine I have a new gear, new Moser 30 spline axles, bearings & studs along with an aluminum rear support cover. It will light them off with that 2.73 gear along with my 383 and a 4100 stall. It works great for having that high gear thanks in part to the engine torque and the bigger stall.
 

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I went from 4.56's to 3.73's and the car was quicker--10.98 vs. 10.81; but then, my car never responds the way others do!
Got 4.30's now--not much fun on the freeway these days.
 

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Here's some real world data for you regarding your gear change question...

Many years ago I still had the stock 307 in my 72 Nova with a TH350 trans w/ shift kit and stock converter. It came stock with 3.08 gears.

3.08 gears - 16.10's in the 1/4 mile
3.73 posi - 15.60's in the 1/4 mile (no other changes)

I basically dropped .5 second in the 1/4 mile just from the gear swap alone. You could really feel it in the seat of the pants too, the car just took off much stronger, wasnt fighting itself to get moving, and got through one gear and got to the next much quicker, not winding out forever, etc.

If you swap to a larger duration cam with the 3.08 gears still in there, its going to have soggy low end performance. If it were me I'd do the 3.73 gear swap first.

Fast forward 12 years later and I still have the same posi unit and 3.73 gears in the car with my current 383 stroker and the car still feels good with those gears. It's not screaming while cruising, I can go on the highway still, and its not a dog out of the hole either like it used to be years ago with the stock gears.

Just my personal experience. A gear swap is a great way to pickup some seat of the pants feel and some real actual performance gains as seen above with my 1/4 mile times.
 
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